1. Field of the Invention
The present invention is directed to programmable hearing aid system, as well as a method for determining optimum parameter sets in a hearing aid.
2. Description of the Prior Art
In a programmable hearing aid several parameter sets are generally stored so as to be selectable by the user. These parameter sets being known as hearing programs. Each of these parameter sets represents the settings, cooperatively matched to one another, of all signal processing parameters for a particular acoustic hearing or environmental situation (e.g. an environmental situation "quiet," i.e. without disturbing background noise, or an environmental situation with low-frequency disturbing noise, etc.). The wearer of the hearing aid can select the suitable hearing program.
A programmable hearing aid of this sort is known from Europearn Application 0 064 042. This hearing aid has a microphone, an earphone, a signal processor and a parameter memory. Up to eight parameter sets can be written into the memory by means of an external programming unit. By the actuation of a switch, the stored parameter sets are called one after the other and are supplied to the signal processor. The user can thus match the signal transmission function of the signal processor optimally to the current hearing situation.
In this known hearing aid system, the parameter set allocated to each hearing situation is determined during the adaptation of the hearing aid, i.e. by a hearing aid acoustician. It is difficult, however, to determine the optimal parameter set for different acoustic environmental situations of the hearing-impaired person in this manner, since the actual acoustic characteristic quantities thereof are finally dependent on individual data. For example, if a hearing aid wearer requires an "in the car" hearing program, because that person often travels in his or her own car, an optimal setting of the parameters for this program must be based on the acoustic characteristic quantities of that car, which in turn depend strongly on the type of car and other factors.
In order to avoid the complicated determination of a suitable parameter set by the hearing aid acoustician, in the hearing aid system disclosed in European Application 0 453 450 an external control apparatus is provided that calculates signal processing parameters to be set from audiometric data, in a complicated method, and calculates characteristic data from the environmental situation. This method is costly, however, and does not always produce an optimal parameter set.
An additional difficulty in the two above-cited methods for determining parameter sets is that even for identical hearing impairment (determined using a sound threshold audiogram), the subjective sensations of different hearing aid wearers can be different in identical acoustic environmental conditions, necessitating different optimal parameter sets for the respective wearers.